Clinical evaluation of the use of Computerized Transaxial Tomography to determine the value of the EMI apparatus in th diagnosis of brain tumors, especially as compared to angiography and pneumoencepalography. Specifically, to attempt to define the capability of the scanner to predict earlier lesions, cystologic type, and the ability to localize lesion s. This study will also determine whether there is a clinical presentation for which either the EMI or nuclide brain scan is the preferable initial diagnostic imaging study, and for which angiography and/or pneumoencepalography are also to be desired. Also to determine absorption data in normal patients.